In recent years, the amount of information, which undergoes processing by digital electronic apparatuses, has been steadily increasing. In response to the increase in the amount of such information, signal speed within such apparatuses also increases. As a result thereof, there is a trend that a transmission margin is decreasing. It is desirable therefore, that various causes of margin degradation be evaluated from a variety of viewpoints and the transmission margin be correctly evaluated.
When the transmission margin of a product is calculated in a conventional way of calculating the transmission margin, a risk that includes a component variation is calculated. For this reason, the following method has been employed. That is, first, a predetermined value that includes a margin with respect to each of the items is used. Then, the predetermined values are summed up in the conventional way of calculation.
As one example of a conventional technique, Japanese Laid-Open Patent Application 2005-278014 discusses a method of measuring a code error rate. In the technique disclosed above, a code error rate at a high-speed system level is measured in a high-speed digital transmission.
However, the number of margins included in determination values of the transmission margin increases in the measurement method discussed above. As a result, it is very difficult to satisfy such determination values. Consequently, the above measurement method results in the use of expensive components in order to satisfy the determination values of the transmission margins, and the use of expensive components causes an increase in overall manufacturing costs. Meanwhile, relatively low yield rates are permissible with regard to certain types of components when such types of components are applied to specific types of products. In order to make determinations on the transmission margins of a variety of products, it is desirable to achieve a system where determination criteria may be flexibly changed depending on circumstances.